Molecular phylogeny of the genus Oryzomys (Rodentia: Sigmodontinae) based on cytochrome b DNA sequences.

The genus Oryzomys comprises 40 species arranged in several species groups. To test the monophyly of three Oryzomys species groups ("capito," nitidus, and subflavus), we analyzed, by distance, parsimony, and maximum-likelihood (ML), 801 bp of the mitochondrial gene cytochrome b. Our results did not sustain the monophyly of Oryzomys nor of the nitidus and subflavus species groups. Within the "capito" species group, O. perenensis appeared as a valid species, as a sister branch of the clade formed by O. megacephalus and O. laticeps. Within the nitidius species group, only the association between O. nitidus and O. lamia was well supported. The subflavus species group split into two clades: one with O. subflavus karyomorphotypes and another grouping O. angouya with species of different genera in the parsimony, distance, and ML trees.